[kevs]

I just got a new 27" with 500 SSD. I don't regret it especially since the Fusion only had 128, not even enough to put the system and apps. I also got brand new USB3 externals, and honestly, I have not notice any speed difference in dealing with files or folders between stuff on the SSD and the same stuff on the externals.

[P]

USB 3 is a big improvement over USB 2 in this respect. USB 3 can optionally use UAS, which fixes the latency problems in USB 2 and earlier (it effectively becomes equivalent to Firewire in this regard).

[kevs]

thanks P, what is UAS.
But USB was faster than Firewire right? It replaced it.

[P]

Hardware speed is not everything, you need to have a protocol to transfer the data as well. USB was never designed for storage, and the best you could do in USB 2.0 and below was something called "bulk only transfer", which was a very primitive protocol. BOT meant that the computer sent one request for data, and then waited until it got it before requesting the next chunk. In practice this means that most of the time is spent waiting for the other device. USB 3.0 has an optional protocol called UAS, USB-attached-SCSI, that works like a modern storage system - effectively, the computer sends out requests on one channel and receives data on the other as it becomes available. Firewire always worked this way (that protocol is called SBP2), so UAS basically evens the playing field.

Note that UAS is not a required part of USB 3.0, so not all devices have it. It is worth checking the spec sheet when buying one.

[kevs]

Thanks P, I understood the gist of that...I bought a new 27" and new USB 3 hardrives so far... those are my guess much faster than Firewire?

[P]

If they use spinning disks, they will likely be the same speed, because the interface will not be the limiting factor. If they are SSDs and use UAS, then yes the USB 3.0 drives will be faster.